Associate 2003-04

You-Hua Chu



Professor Chu has studied the ionized interstellar gas in the Milky Way galaxy and the Magellanic Clouds using ground-based telescopes and space observatories. During her Center appointment she will study the hot (millions of degrees Kelvin) interstellar gas in more distant galaxies, using x-ray observations made at the Chandra X-ray Observatory.

Galaxies are the basic building units in the universe. They evolve as they interact with neighboring galaxies or as their own stars form and die. Over time a number of x-ray sources are produced, and observations of these sources can shed light on the evolutionary history of the host galaxy itself. X-ray observations of our Milky Way galaxy are difficult, however, because of the obscuring effect caused by dust and gas in the galactic plane. Observations of distant galaxies have also been difficult because of limited angular resolution of x-ray telescopes. Chandra is the first x-ray observatory that allows a clear separation of point sources containing blackholes or neutron stars from the diffuse sources of the hot interstellar gas in galaxies at distances out to 100 million light years. Observations of about 100 nearby galaxies are available in the Chandra archive. Professor Chu will take advantage of this dataset to make a systematic study of the content, distribution, physical conditions, and evolution of the hottest interstellar gas in both elliptical and spiral galaxies. Her results will provide a better understanding of the heating of interstellar gas by supernovae, fast stellar winds from massive stars, and jets from supermassive blackholes in galactic centers.